Rainbow 🌈 mind map and MCQ Properties of Light

Speed Up Science • Rainbow Mind Map

Properties of Light

Learn rectilinear propagation, reflection, refraction, total internal reflection, dispersion and scattering with a responsive mind map, animated prism and self-check MCQ activity.

Overview Propagation Reflection Refraction Dispersion Scattering MCQ Quiz FAQ

Rainbow Mind Map: Properties of Light

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Rectilinear Propagation

Light travels in a straight line through a uniform transparent medium.

Shadows • Pinhole camera

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Reflection

Light returns to the same medium after striking a reflecting surface.

Mirrors • Periscopes

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Refraction

Light changes speed and direction when it enters another transparent medium.

Lenses • Microscopes

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Total Internal Reflection

Light is completely reflected inside a denser medium under special conditions.

Optical fibre • Prisms

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Dispersion

White light separates into seven visible colours.

Prism • Rainbow

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Scattering

Particles and molecules redirect light in different directions.

Blue sky • Red sunset

1. Rectilinear Propagation and Speed of Light

Rectilinear propagation means that light travels along straight paths through a uniform transparent medium. This explains sharp shadows and the working of a pinhole camera.

c = 299,792,458 m/s ≈ 3 × 10⁸ m/s

The speed of light is greatest in vacuum. It becomes lower in transparent materials such as water, glass and diamond.

A pinhole camera works because light travels in straight lines.

2. Reflection of Light

Reflection is the return of light into the same medium after it strikes a surface. We see most objects because reflected light reaches our eyes.

First Law

The incident ray, reflected ray and normal lie in the same plane.

Second Law

The angle of incidence is equal to the angle of reflection.

∠i = ∠r

Reflection returns light to the original medium.

3. Refraction and Total Internal Reflection

Refraction is the bending of light when it passes from one transparent medium to another because its speed changes.

Refractive index: n = c ÷ v

Total internal reflection occurs when light travels from an optically denser medium to a rarer medium and the angle of incidence is greater than the critical angle.

• Optical fibres use total internal reflection to carry light signals.
• Prisms use it to change the direction of light.
• A mirage is commonly explained by atmospheric refraction followed by total internal reflection.

Light bends when its speed changes between transparent media.

4. Dispersion of Light

Dispersion is the splitting of white light into its constituent colours. The order is commonly remembered as VIBGYOR: violet, indigo, blue, green, yellow, orange and red.

Rainbow formation: Sunlight is refracted and dispersed when it enters water droplets, reflected inside them and refracted again as it leaves.

5. Scattering of Light

Scattering occurs when light is redirected by molecules, dust particles, water droplets or other small particles.

• Blue sky: shorter wavelengths are scattered more strongly by atmospheric molecules.
• Red sunrise and sunset: sunlight travels through more atmosphere, so much of the blue light is scattered away.
• Red danger signals: red light is scattered less and can remain visible from a greater distance.

Interactive Concept Explorer

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Reflection Refraction Dispersion Scattering

Reflection

Light bounces back from a surface. A mirror is a familiar example.

Refraction

Light bends when its speed changes while entering another transparent medium.

Dispersion

A prism separates white light into its visible colours because each colour bends differently.

Scattering

Particles redirect light. This helps explain the blue sky and reddish sunsets.

Rainbow MCQ Quiz on Properties of Light

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1. Light travels in a straight line through a uniform medium. This is called:

Perpendicular propagation Rectilinear propagation Scattering Reflection Reveal answer

Correct answer: Rectilinear propagation. It states that light travels in a straight path through a uniform transparent medium.

2. The speed of light is maximum in:

Solids Water Vacuum All media equally Reveal answer

Correct answer: Vacuum. Light travels at approximately 3 × 10⁸ m/s in vacuum.

3. Returning of light into the same medium is called:

Reflection Refraction Dispersion Scattering Reveal answer

Correct answer: Reflection.

4. Bending of light when it passes from one medium to another is called:

Reflection Refraction Absorption Scattering Reveal answer

Correct answer: Refraction. It occurs because light changes speed in the new medium.

5. A mirage is commonly explained by atmospheric refraction followed by:

Dispersion Total internal reflection Rectilinear propagation Absorption Reveal answer

Correct answer: Total internal reflection.

6. Splitting white light into seven visible colours is called:

Reflection Dispersion Scattering Absorption Reveal answer

Correct answer: Dispersion.

7. The Sun appears redder near the horizon mainly because:

Red light is scattered less than shorter wavelengths Red light is scattered the most The Sun becomes cooler Reflection stops Reveal answer

Correct answer: Red light is scattered less than shorter wavelengths.

Frequently Asked Questions

What is rectilinear propagation of light?

It means that light travels in straight lines through a uniform transparent medium. It explains shadows and the working of a pinhole camera.

Why does light bend during refraction?

Light bends because its speed changes when it passes from one transparent medium to another.

What are the conditions for total internal reflection?

Light must travel from an optically denser medium to a rarer medium, and the angle of incidence must be greater than the critical angle.

How is a rainbow formed?

A rainbow forms through refraction, dispersion, internal reflection and further refraction of sunlight inside water droplets.

Why does the Sun appear reddish at sunrise and sunset?

Sunlight travels through a longer atmospheric path. Shorter wavelengths scatter more strongly, leaving more red and orange light to reach our eyes.

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Concept by Teacher Ritu • Designed by Shaleen Shekhar • Speed Up Science